Thanks for the Chrome details, gbagur — and for taking the time to write all this up! Update 0.8.20 is now live. It adds a Quests tab to the journal (H), lets you choose the Current Oath, clarifies equipment slots, improves keyboard navigation with Backspace as an alternative to Esc, smooths the crossings, and fixes the clipped spell-upgrade cards. I also checked both upgrade schools for all eight spells, including saving and reloading them.
The update reduces several measured performance bottlenecks, especially offscreen fire lighting and long enemy path searches. I cannot promise that your random slowdown is completely gone, so please let me know if it still happens. Loot balance is unchanged for now.
Full notes and a quest-journal screenshot: https://valentusss.itch.io/ashentrail/devlog/1756577/0820-quest-tracking-smoothe...
Thank you again for helping improve the game!